[A comparative study of nitric oxide (NO) gas solution, L-arginine and D-arginine on superoxide anion radical...

Nitric oxide (NO) has been studied from various aspects since NO had been recognized as an endothelium-derived relaxing factor (EDRF). We studied the effect of NO gas solution, L-arginine and D-arginine on superoxide anion radical (O2-) generation using human polymorphonuclear leukocytes by chemiluminescence method. NO gas solution inhibited O2- generation induced by fMLP or PMA in a dose-dependent fashion, whereas L-arginine that in NO precursor increased O2- generation. On the other hand, D-arginine which is an optical isomer, had no effect on O2- generation. These results suggest that L-arginine administered externally may be different from endogenous L-arginine and has a different effect on O2- generation. Therefore, we must pay attention to biological effects of L-arginine when experiments are performed on nitric oxide.